Integrated circuits (ICs) are typically housed within a plastic or ceramic package. The packages have leads or surface pads that are soldered to a printed circuit board. The circuit board and package are often located within an enclosed computer chassis that contains other circuitry associated with the computer system such as peripherals, memory cards, video cards, power supplies, etc. The computer chassis typically contains fans that remove the heat generated by the IC and other system components.
It is desirable to have a high rate of heat transfer from the IC package in order to maintain the junction temperatures of the IC within safe operating limits. Modern microprocessors typically employ millions of transistors in internal circuitry that require some type of cooling mechanism, otherwise, excessive junction temperatures may affect the performance of the circuit and cause permanent degradation of the device. Further, in order for computer system manufacturers to remain profitable while facing the precipitous price erosion of computer systems, the manufacturers need to analyze and attempt to reduce the pricing of each computer system component. Hence, having a standardized, efficient, reliable and cost effective heat removal methods has become critical in the design of computer system enclosures. One prior art system utilizing an exhaust fan and some air ducts for cooling in a computer system enclosure is shown in FIGS. 1A, 1B and 1C (Nelson in U.S. Pat. No. 5,691,883, issued on Nov. 25, 1997).
FIG. 1A illustrates a top view of the prior art system. Enclosure 10 comprises a variety of components including a power supply 17, microprocessor 14, peripherals 24 and cards 16. Cards 16 may comprise any of a number of components, such as, for example, memory cards, modem cards, video cards, daughter boards, etc.. Peripherals 24 may include a floppy or hard disk driver or a number of other peripheral devices commonly known in the art.
Enclosure 10 is divided primarily into three sections. These include card slot and Peripheral compartment 25, power supply compartment 11, and air duct 13. As illustrated, compartment 25 contains peripherals 24 and cards 16. Compartment 11 contains power supply 17 and the cooling system fan 12. Air duct 13 houses the computer system processor 14.
The cooling fan 12 of the present invention resides in power supply compartment 11. fan 12 pulls air into enclosure 10 by creating a low pressure zone within the power supply compartment 11. Air duct 13 provides an air flow path from opening 26, at the exterior of enclosure 10, to an inlet opening 29 of compartment 11. The air duct is configured to direct cool air from the exterior of enclosure 10 across processor 14. By passing cool, unheated air over processor 14, a maximum achievable heat transfer is established across the processor. As the air flow passes over processor 14, it is heated. The heated air then passes along air duct 13 into compartment 11 through opening 29. In order to provide cooling to compartment 25, an air flow is established by providing openings 20 and 21 within air duct walls 18 and 19, respectively. (See FIGS. 1B and 1C.)
Although the cooling method and system of FIG. 1 is well established, some problems still exist. First, the enclosure with the previously described air duct, the fan, and all the openings can only operate with certain computer board designs. In other words, since components such as the power supply, various add-on cards, etc. can only reside in particular compartments of the enclosure, users' abilities to upgrade their computer boards and reuse the enclosure are severely hampered. Secondly, the cooling mechanism seems to focus more on the processor and not the rest of the system. As a result, other compartments of the enclosure will not receive cool, ambient air directly from the exterior of the enclosure, but will instead receive heated air after the air has already passed over the processor. Thus, cooling to other parts of the computer system may be ineffective, and more heat sinks are likely required to compensate for this shortcoming. Undoubtedly, these additional heat sinks will increase the cost of manufacturing computer systems. Lastly, the prior art describes a cooling mechanism which is built into the computer chassis. Because of the extra complexity in including the cooling system in the chassis's structure, implementing the invention described in FIG. 1A is certainly more costly than building the cooling and structural components separately and then assembling them together.
Therefore, an apparatus and method is needed to solve the aforementioned problems associated with using an one fan cooling system which is part of a computer system enclosure.